package com.wtx.chapter11;

/**
 * @description: 第二版的并查集
 * @author: wtx
 * @createDate: 2020/6/1
 */
public class UnionFind2 implements UF{

    private int[] parent;

    public UnionFind2(int size) {
        parent = new int[size];
        for (int i = 0; i < size; i++)
            parent[i] = i;
    }

    private int find(int p){

        if (p<0 || p>=parent.length)
            throw new IllegalArgumentException("p is out of bound");
        while (p!=parent[p])
            p = parent[p];
        return p;
    }

    @Override
    public boolean isConnected(int p, int q) {
        return find(p) == find(q);
    }

    //合并操作的性能较第一版高
    @Override
    public void unionElements(int p, int q) {

        int pRoot = find(p);
        int qRoot = find(q);

        if (pRoot == qRoot)
            return;

        parent[pRoot] = parent[qRoot];
    }

    @Override
    public int getSize() {
        return parent.length;
    }
}
